Naturally acquired humoral and cellular immune responses to Plasmodium vivax merozoite surface protein 8 in patients with P. vivax infection

• Published in: Malaria Journal
• Main Authors: Yang Cheng, Bo Wang, Siriruk Changrob, Jin-Hee Han, Jetsumon Sattabongkot, Kwon-Soo Ha, Patchanee Chootong, Feng Lu, Jun Cao, Myat Htut Nyunt, Won Sun Park, Seok-Ho Hong, Chae Seung Lim, Takafumi Tsuboi, Eun-Taek Han
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2017
• Subjects: Plasmodium vivax; Merozoite surface protein 8; Immunogenicity; Food vacuole; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-017-1837-5; https://doaj.org/article/c4252c00a1004e2488833bd550477c6b

Abstract Background Thirty-one glycosylphosphatidylinositol (GPI)-anchored proteins of Plasmodium vivax, merozoite surface protein 1 (MSP1), MSP1 paralogue, MSP4, MSP5, MSP8, and MSP10 have been reported from homologs of Plasmodium falciparum by gene annotation with bioinformatics tools. These GPI-anchored proteins contain two epidermal growth factor (EGF)-like domains at its C-terminus. Here, P. vivax merozoite surface protein 8 (PvMSP8) are considered as potential targets of protective immunity. Methods Recombinant PvMSP8 (rPvMSP8) was expressed, purified, and used for the assessment of humoral and cellular immune responses in P. vivax-infected patients and immune mice. Moreover, the target epitope of ant-PvMSP8 antibodies and subcellular localization of PvMSP8 was also determined. Results The rPvMSP8 was successfully expressed and purified as soluble form as ~55 kDa. PvMSP8 was localized to the outer circle of pigments associated with the food vacuole. The rPvMSP8 protein had a high antigenicity (73.2% in sensitivity and 96.2% in specificity) in patients infected with P. vivax. IgG2 antibody subtype was the predominantly responses to this antigen. Antibody response to PvMSP8 increased up to day 7 and after that slightly decreased within a month. The longevity of anti-PvMSP8 antibody was stably sustained up to 12-year recovery patient samples. Most anti-PvMSP8 antibodies recognized two epitopes that were located outside the C-terminal EGF-like domain. The cellular immune response in P. vivax-exposed individuals produced high levels of IFN-γ and IL-10 upon PvMSP8 antigen stimulation in vitro. Conclusions All data in this study suggest that PvMSP8 antigen has a potential to induce both humoral and cellular immune responses in patients with P. vivax infection. The subcellular localization of PvMSP8 confirmed that it was associated with the parasite food vacuole in blood-stage parasites. A further characterization of this protein will be useful for blood stage P. vivax vaccine development.